This invention relates to the field of telecommunications. More particularly, a system and methods are provided for identifying and propagating called-party information through a telephone network for use in a centralized voice mail service.
A central or network voice mail provider (VMP) offers voice mail services to subscribers by receiving, at a central location, voice mail messages directed to those subscribers. Receiving and storing the messages at a central location eliminates any need for the subscribers to maintain their own telephone answering devices. Typically, when a calling party calls a called party who is a subscriber to a central voice mail service, if the subscriber does not answer his or her telephone the call is forwarded to the VMP. The VMP then records and stores a voice mail message from the calling party. The subscriber can then connect to the VMP and retrieve the message at a later time.
As one example of how central voice mail services have been provided, a local telephone company or Local Exchange Carrier (LEC) (or an entity connected to the telephone company""s or LEC""s switch) may be configured to provide voice mail services within the LEC""s area, or possibly throughout its LATA (Local Access and Transport Area). The LEC generally cannot, however, provide voice mail service to a subscriber that is not connected to its switch. Thus, to provide central voice mail services regionally or nationally (i.e., across multiple local areas), a VMP could establish a presence in each local area (e.g., by configuring call servers connected to every local switch), but this would entail great expense.
Instead of establishing a presence in each local area, a voice mail provider could establish a central regional or national presence and have subscribers"" calls forwarded to and handled at the central location. In this scenario, however, the subscribers that are not local to the central location could incur long-distance charges for each call forwarded to the VMP (for recording), and when accessing the system to retrieve messages. Thus, in order to establish a central voice mail service on a regional or national basis, existing systems either require a VMP""s presence in every subscriber""s area or lead to long-distance charges.
Further, with a central voice mail system, in order to ensure that messages are recorded for the correct parties, the system must be able to identify the target subscriber of each call it handles. This is usually done by assigning an additional telephone number to a subscriber (i.e., a forward-to number) that can be associated with the subscriber when a call is received at that number at the VMP. Because of the scarcity of telephone numbers in some areas, however, it may not be possible to obtain another number (especially a local number) for each voice mail subscriber.
Therefore, it would be helpful to be able to identify a called subscriber through the telephone signaling information received with a call. For example, telephone signaling data may, depending on the signaling protocol or switching system, include information such as caller identification, ANI (Automatic Number Identification), DNIS (Dialed Number Identification Service), etc. However, some information that may be used by a VMP to identify a subscriber (e.g., the subscriber""s telephone number) is often omitted or dropped from the signaling (e.g., when the call is transferred from one switch to another).
For example, Direct Inward Dialing (DID) is a service offered by LECs that enables one attempted solution to the desire for a centralized voice mail system. However, this solution suffers from the problems identified above, in that it requires a separate forward-to telephone number for each subscriber and the subscriber may incur long distance charges if the forward-to number is not local. With DID, when a call to a subscriber is forwarded to a voice mail provider, the subscriber""s actual telephone number (i.e., the OCN or Original Called Number) is not sent in the signaling information that accompanies the forwarded call. The VMP can therefore only identify the called subscriber by the forward-to number. If one central (forward-to) number were used for multiple subscribers, the VMP would not be able to distinguish a call for one of the subscribers from a call for another.
Thus, with existing centralized voice mail systems, voice mail providers must establish a presence in each subscriber""s local area, or at least every area to which subscriber""s telephone calls are forwarded. But, the scarcity of telephone numbers in some areas may prevent some would-be subscribers from receiving local forward-to numbers. Existing voice mail systems cannot provide centralized services on large (e.g., regional or national) basis because users are generally unwilling to accept the long-distance charges that may be incurred when calls to them are forwarded to a VMP presence outside of their local area. In addition, using one forward-to number for multiple voice mail subscribers is not feasible when calls are forwarded long distances, because some telephone switching systems do not forward the information needed to identify a called subscriber.
Therefore, in one embodiment of the invention a system and methods are provided for enabling centralized voice mail services over a large area (e.g., regionally or nationally) without assigning additional telephone numbers for each subscriber. In this embodiment, a central VMP is provided with called party information in order to identify a called subscriber even if the telephone signaling system normally does not forward this information.
In an embodiment of the invention, a telephone call originated from a calling party to a called party is received at a telephone switch coupled to a third party (e.g., a provider of telephone services, such as voice mail) because the called party""s telephone service is configured to forward the call to the third party. At the switch, information concerning the called party is retrieved from a first set of call data that is configured according to a first telephone signaling protocol (e.g., Signaling System 7). A second set of call data is assembled for transmission to the third party according to another telephone signaling protocol (e.g., SMDI, ISDN PRI). In this embodiment, this other telephone signaling protocol normally excludes the called party information or, alternatively, includes a field that is configured to store data for identifying the called party, but that field of data is not received at the switch through the first protocol.
The called party information is stored in the second set of call data in place of other information and the call data is transmitted to the third party with the forwarded call. The third party can then use the information to identify the called party for purposes of recording a voice mail message, playing a greeting for the calling party from the called party, billing the called party, or for some other reason.